POJ 2406 Power Strings KMP 或者后缀数组

找最小循环节

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <queue>
#define INF 0x3f3f3f3f
using namespace std;

char B[1000010];
int nex[1100000];
int lenB;
void getNex(){
lenB = strlen(B);
nex[0] = -1;
int i = 0,j = -1;
while(i < lenB){
if(j == -1 || B[i] == B[j]){
++j,++i;
if(B[i]!=B[j]){
nex[i] = j;
}
else{
nex[i] = nex[j];
}
}
else{
j = nex[j];
}
}
}
int main(){
int n;
while(scanf("%s",B)){
if(!strcmp(B,".")) break;
getNex();
if(lenB%(lenB-nex[lenB])==0){
printf("%d\n",lenB/(lenB-nex[lenB]));
}
else puts("1");
}
return 0;
}


#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <queue>
#define INF 0x3f3f3f3f
using namespace std;
#define F(x) ((x) / 3 + ((x) % 3 == 1 ? 0 : tb))
#define G(x) ((x) < tb ? (x) * 3 + 1 :((x) - tb) * 3 + 2)
const int MAXN = 3000001;
int wa[MAXN],wb[MAXN],ws[MAXN],wv[MAXN],wsd[MAXN],r[MAXN],sa[MAXN];
int c0(int *r,int a,int b)
{return r[a] == r[b] && r[a + 1] == r[b + 1] && r[a + 2] == r[b + 2];}
int c12(int k,int *r,int a,int b)
{if(k == 2) return r[a] < r[b] || r[a] == r[b] && c12(1,r,a + 1,b + 1);
else return r[a] < r[b] || r[a] == r[b] && wv[a + 1]< wv[b + 1];}
void sort(int *r,int *a,int *b,int n,int m)
{
int i;
for(i = 0 ; i < n ; i++) wv[i] = r[a[i]];
for(i = 0 ; i < m ; i++) wsd[i] = 0;
for(i = 0 ; i < n ; i++) wsd[wv[i]]++;
for(i = 1 ; i < m ; i++) wsd[i] += wsd[i - 1];
for(i = n - 1 ; i >= 0 ; i--) b[--wsd[wv[i]]] = a[i];
}

void dc3(int *r,int *sa,int n,int m)
{
int i,j,*rn = r + n ,*san = sa + n,ta = 0,tb = (n + 1) / 3,tbc = 0,p;
r
= r[n + 1] = 0;
for(i = 0 ; i < n ; i++) if(i % 3 != 0) wa[tbc++] = i;
sort(r + 2,wa,wb,tbc,m);
sort(r + 1,wb,wa,tbc,m);
sort(r,wa,wb,tbc,m);
for(p = 1,rn[F(wb[0])] = 0,i = 1 ; i < tbc ; i++)
rn[F(wb[i])] = c0(r,wb[i - 1],wb[i])?p - 1 : p++;
if(p < tbc) dc3(rn,san,tbc,p);
else for(i = 0 ; i < tbc ; i++) san[rn[i]] = i;
for(i = 0 ;i < tbc ; i++) if(san[i] < tb) wb[ta++] = san[i] * 3;
if(n % 3 == 1) wb[ta++] = n - 1;
sort(r,wb,wa,ta,m);
for(i = 0 ; i < tbc ; i++) wv[wb[i] = G(san[i])] = i;
for(i = 0,j = 0,p = 0 ; i < ta && j < tbc ; p++)
sa[p]=c12(wb[j] % 3,r,wa[i],wb[j]) ? wa[i++] : wb[j++];
for(;i < ta ; p++) sa[p] = wa[i++];
for(;j < tbc ; p++) sa[p] = wb[j++];
}
int Rank[MAXN],height[MAXN];
void calheight(int *r,int *sa,int n)
{
int i,j,k = 0;
for(i = 1 ; i <= n ; i++) Rank[sa[i]] = i;
for(i = 0 ; i < n ; height[Rank[i++]] = k)
for(k ? k--:0,j = sa[Rank[i] - 1] ;r[i + k]==r[j + k];k++);
}
char str[MAXN];
int a[MAXN];
int ans[MAXN];
void init(int n){
// for(int i = 0; i < n; ++i){
// cout<<Rank[i]<<" ";
// }
// cout<<endl;
// for(int i = 0; i < n; ++i){
// cout<<height[Rank[i]]<<" ";
// }
// cout<<endl;
int k = Rank[0];
ans[k] = n;
for(int i = k+1; i <= n; ++i){
ans[i] = min(ans[i-1],height[i]);
// cout<<i<<" "<<ans[i]<<endl;
}
for(int i = k-1; i >= 0; --i){
ans[i] = min(ans[i+1],height[i+1]);
// cout<<i<<" "<<ans[i]<<endl;
}
}
int solve(int n){
for(int i = 1; i <= n/2; ++i){
if(n%i!=0) continue;
// cout<<ans[Rank[i]]<<endl;
if(ans[Rank[i]]==n-i)
return n/i;
}
return 1;
}
int main(){
int n;
while(~scanf("%s",str)){
if(!strcmp(str,".")) break;
n = strlen(str);
for(int i = 0; i < n; ++i){
a[i] = str[i];
}
a
= 0;
dc3(a,sa,n+1,257);
calheight(a,sa,n);
init(n);
int ans = solve(n);
printf("%d\n",ans);
}
return 0;
}